Referring to FIG. 37, one example of conventional thermal print heads is illustrated (see, e.g., Japanese Patent Laid-Open Re-Publication No. 2005-120841). A thermal print head 900 shown in FIG. 37 includes a ceramic substrate 91 and a wiring substrate 92. A glaze layer 93 is formed in the ceramic substrate 91. The glaze layer 93 is made of, e.g., glass, and has an arc-like cross-sectional shape when seen in a direction perpendicular to a primary scanning direction. An electrode layer 94 is also formed in the ceramic substrate 91. The electrode layer 94 is mainly composed of, e.g., Au, and includes a plurality of individual electrodes 941 and a common electrode 942. A resistor layer 95 and a protective layer 96 are formed one above another on the electrode layer 94. The resistor layer 95 is formed to straddle the individual electrodes 941 and the common electrode 942. The protective layer 96 is formed to protect the electrode layer 94 and the resistor layer 95 and is made of, e.g., glass. A drive IC 97 is mounted to one end of the ceramic substrate 91 in a secondary scanning direction. The drive IC 97 functions to partially apply an electric current to the resistor layer 95 through the individual electrodes 941. The drive IC 97 is connected to the individual electrodes 941 and the wiring substrate 92 by wires 98.
A thermal paper as a print target is pressed against the resistor layer 95 through the protective layer 96. This pressing operation is performed by a platen roller (not shown) provided in a printer incorporating the thermal print head 900. If the pressing force applied by the platen roller reaches the area where the individual electrodes 941 and the common electrode 942 exist, it is likely that the portion of the resistor layer 95 covering the individual electrodes 941 and the common electrode 942 may suffer from damage. Japanese Patent Laid-Open Re-Publication No. 2005-120841 discloses a configuration in which the individual electrodes 941 and the common electrode 942 are sunk with respect to the glaze layer 93. However, it becomes difficult to sink the individual electrodes 941 and the common electrode 942 as the glaze layer 93 grows thinner with the reduction in the thickness of the thermal print head 900. Under these circumstances, it is impossible to avoid damage to the resistor layer 95.